Horizontal lines appearing on your LCD monitor can mean one of two things: Either your monitor isn't set to optimal settings or internal hardware is failing. If you want to try setting your LCD monitor to an optimal configuration, you must know how to do it properly. Configuring an LCD monitor involves altering the brightness, the colors and the contrast settings within the display menu of your monitor.
Navigate to the Lagom LCD test website.
Click any one of the tests. For horizontal lines, calibrate the clock and phase of your monitor.
Follow the on-screen instructions. Each test will tell you how the image will appear at optimal settings. Consult your manual for instructions specific to your monitor, because all monitors are different.